Heat-insulating composition and abticles made therefrom



UNITED STATES PATENT OFFICE.

FRANK A. HEADSON; 0F MILWAUKEE, WISCONSIN.

HEAT-INSULATING- COMPOSITION AND ARTICLES MADE THEREFROM.

No Drawing.

blocks, heat-insulating filler for the walls of fire-boxes, blast furnaces, ovens or similar structures which are subjected to a high degree of heat.

The principal object of the invention is to provide a simple, economical and efiicient heat-insulating composition or compound, adapted. to be used in making bricks, blocks, or as a heat-isulating filler for blast furnace walls, or other articles or structures suitable for heat-insulating purposes under conditions where such composition is subjected to a high degree of heat.

Other and further objects of the invention will appear from the following description, and from an inspection of the accompanying drawings, which are made a part hereof.

Matter herein described and shown, but not claimed, and the improved process herein described, but not claimed herein, will be found described and claimed in a co-pending application for Letters Patent of the United States, Serial No. 143,722, filed by me on January 22, 1917, for process of making a heat-insulating composition, and also in an application, Serial No. 256,500, filed of even date, herewith in my name, for Letters Patent of the United States for' improvements in heat-insulating compositions and articles made therefrom, to which reference is made.

This invention consists in the combination of elements and in the heat-insulating composition or compound,and articles made therefromherein described and claimed.

In making a composition of matter or material for heat-insulating purposes, and articles of manufacture, such as a filler for furnace walls, heat-insulating bricks, or similar structures in accordance with my invention, I provide a suitable quantity of diatoma- Specification of Letters Patent.

Patented June 24, 1919.

Application filed October 2, 1918. Serial 110,256,501.

ceous earth, or diatomaceous earth and asbestos, for making a batch of the material, and a suflicient quantity of water for moistening the same.

The diatomaceous earth sometimes called kieselguhr, infusorial earth, or silicaand the asbestos are disintegrated, pulverized, or reduced to a finely divided state by grinding or crushing said materials in any suitable ordinary and well known manner, I prefer to disintegrate or pulverize the diatomaceous earth and the asbestos separately, and then to interinix them in suitable proportions, and add to the mixture a sufficient quantity of water to moisten the mass so that it will be of the desired consistency for molding in an eflicient manner, although it will be readily understood that the diatomaceous earth and asbestos may be ground or pulverized to any desired extent after being mixed together in suitable proportions. I have found in practice that a composition of matter or compound for heat-insulating purposes may be made in accordance with my invention by combining and treating the following described elements in the followlng proportions, and in the manner herein described Diatomaceous earth, 7 5 per cent; .Asbestos (finely divided), 25 per cent, and

Water suflicient to moisten the mass to the desired consistency suitable for molding.

It will be readily understood by those skilled in the art that the proportions of diatomaceous earth and asbestos may be varied to aconsiderable extent without depart ing from the spirit of my invention, al-

though the use of the above mentioned ele- 5 ments in the proportions above set forth, or, in approxlmately the proportions designated has been found in practice to be quite satisfactory for the purposes for which the invention is intended.

The material consisting of or comprising diatomaceous earth and asbestos, in approximately the above mentioned proportions, when moistened with water, is, by prefer.-

ence, thoroughly stirred or puddled so as 105 to be of uniform consistency throughout and form a homogeneous mass of suitable consistency for molding.

The mixture may be worked or puddled for several hours or for any desired length 110 of time, until it is of the desired uniform consistency throughout, suitable for molding as above indicated, and then molded, cut or formed into bricks, blocks, slabs or similar articles suitable for use for heat-insulating or heat-resisting purposes when completed.

During the operation of molding, the material to be operated upon is, by preference, subjected to pressure, the degree of wh1ch may vary in accordance with the size or dimensions of the article to be molded. A pressure of approximately 200 pounds per square inch is sufiicient and satlsfactory in most instances. Greater pressure should be employed in molding relatively large articles or blocks, and relatively less pressure would be required for articles of comparatively small dimensions. The pressure should ordinarily be sufficient to properly form the article to be molded, as will be readily understood by those skilled in theart. The proportion of water used for making molded articles should :be suiiiclent to properly moisten the mass to thedeslred consistency for molding in an efiiclent manner without causing water to run out of the mold during the molding operation, or whlle the mass is being subjected to the desired pressure.

I have found in practlce that entlrely satisfactory results are obtained by molstemng the mass of diatomaceous earth and ashestos, both in a finely divided condition, with a quantity of water equivalent to approx mately one-third of the weight of the or1g1- nal mass to be moistened thereby.

After molding the material into the form of bricks, slabs or other articles, the articles are thoroughly dried. This may be accomplished by heating the material or art cle to a suflicient temperature for a sufliclent length of time to thoroughly remove all moisture from the material. The bricks, slabs, or other articles thus obtained, after having been thoroughly dried, are, when de sired, placed in. a kiln and burned or calcined.

Bricks, slabs, or other articles suitable for heat-insulating purposes and consisting of diatomaceous earth and asbestos, commlnuted. and intermixed in suitable proportions, as above indicated, are, in the process of burning, subjected to a gradually increasing temperature such as will not cause unnecessary cracking, until a temperature sufficient to calcine, bake or burn the material, preferably at a red heat, is reached.

The calcining or burning temperature indicated is maintained for a suflicient length of time to properly bake, calcine or burn the material. The time and degree of temperature. may vary according to the degree of hardness desired, or according to the degree of temperature to which the material or article is to be subjected in use. In practice, satisfactory results have been obtained by subjecting the material to a temperature of approximately 2000 F. to 2800 F., and maintained for a period of from 9 to 144 hours, or thereabout, according to the degree of hardness of the material desired, or according to the degree of temperature to which the material is to be subjected in use, as already suggested. The articles or material having thus been calcined or burned for the desired length of time and at the desired temperature, are allowed to gradually cool, and are then in finished form and ready for use for heat-insulating purposes, or for any desired purpose.

It has been found in practice that bricks, slabs, blocks or similar articles made of material such as diatomaceous earth, or diatomaceous earth and asbestos, comminuted and intermixed, but not calcined or burned before being molded or formed, are liable to shrink and, in some instances, to warp or to become distorted during the process of burn ing the same or When subjected to the action of heat when in use: It is of course very desirable that such shrinking and warping of the molded or completed material or articles be prevented. In order to accomplish this and to provide a heat-insulating material or composition, or articles made therefrom, I provide a suitable quantity of diatomaceous earth, or diatomaceous earth and finely divided asbestos, which I reduce to a finely divided state or comminuted form by grinding or crushing the same in or by means of a suitable crushing device which may be of any ordinary well known or desired form. Said material is calcined or burned before being molded, which operation of calcining may be accomplished by subjecting the material to a temperature, by preference, suflicient to bring the material to a red heat, but below the melting point of the material. A temperature of approximately 2000 F. to 3000 F. or more, but, by preference, below the fluxing temperature of the material, and above the temperature to which the material is to be subjected in use, maintained for a period of approximately six hours more or less, has been found to produce satisfactory results. The temperature may vary to a considerable extent above or below the stated degrees of temperature, and the time of burning may be in excess of, or less than the time above mentioned, according to the temperature to which the material is to be subjected in use. In practice, I prefer to subject the diatomaceous earth in a finely divided state to a temperature equal to or in excess of the temperature to which it or the finished compound is to be subjected in use, and for a sufficient length of time to thoroughly calcine the diatomaceous earth or kieselguhr, before intermixing it with the asbestos either in a raw uncalcined or calcined finely divided state, thus producing a composition containing said elements, preferably in substantially the-proportions of 75 per cent. of calcined diatomaceous earth and 25 per cent. of finely divided asbestos, in a raw or calcined state, but preferably cal cined, which is suitable for use in its dry form as a filler for blast-furnace walls, or for being moistened with water, with or without the additionof a binder of bonding clay or similar fire-resisting material, and then compressed or molded into the form of heat-insulating bricks, blocks or similar articles or structures, either before being again burned or calcined or with again burning or calcining the material.

When the compound is to be made into heat-insulating bricks or blocks, or similar structures, the intermixed calcined or burned diatomaoeous earth and asbestos in a finely divided state, are, by preference, moistened by the addition of a liquid, such as water, or by adding a suitable quantity of other moistening or binding, material. The binding material may be in the form of what is commonly known as refractory bonding clay or potters clay in moist or plastic form. When such a binder is used, I find that very satisfactory results are obtained by employing a quantity of binding material or bonding material equivalent to approximately 3 to 10 per cent. of the bulk of the entire mass. The material thus obtained, either with or without bonding clay, but, by preference containing the binder or bonding clay as above indicated, is adapted to be used for making heatinsulating bricks, blocks, or walls of furnaces, or a heat-insulating filler for blast furnace walls, or other structures. The material or mixture in its calcined, baked or burnedcondition, and with the diatomaceous earth calcined or burned, and used preferably with asbestos, is molded or formed into the shape in which it is intended to be used. The molding may be accomplished by means of an ordinary brick-molding or brick-pressing machine, which machines are well known; and it is therefore deemed unnecessary to illustrate or describe the samein this application in order to enable the invention to be understood. After molding the material, the material in its molded form, or in the shape in which it is intended to remain, may be again subjected to, a further operation of burning at a suitable temperature such, for instance, as approximately 2000f F. to 3000 F., more or less, for any deslred suitable length of time, for instance, approximately six hours more of less. Such second or final burnino or calcining operation will not cause the material to shrink or warp to any appreciable extent, if at all.

By making the material or mlxture herein described, sufiiciently soft and plastic by the introduction of a sufficient quantity or proportion of liquid or moistening material, the said material or mixture forms a very satisfactory and desirable heat-insulating cement adapted for use in laying heat-resisting bricks, or blocks, and for making heat-insulating walls of or containing such material, or for other purposes.

The calcined, baked or burned diatomaceous earth, after having been subjected to a temperature of approximately 2000 F. to 3000 F., more or less, and by preference, equal to or in excess of the highest temperature to which the material is intended to be subjected in use, for a period of from 9 to 144 hours, or a sufficient length of time to produce the desired degree of hardness, and said material having been comminuted or crushed to a finely divided state preferably before being calcined and before being intermixed with the absestos, and then intermixed with the finely divided asbestos in either a raw and unbaked, unburned and uncalcined state, or in a calcined state, and in any desired suitable proportions, and either with or without a binder, such, for instance, as refractory or bonding clay, is adapted to be handled and sold and dealt in or used in its dry form, and without or before being moistened and rendered plastic, and molded or formed, into the form of bricks or blocks, or similar form in which it is intended to be used; and it may then be moistened or rendered plastic, and molded or formed into the shape in which it is intended to be used, if desired, at any convenient place and time.

It is obvious thatthe material consisting of calcined diatomaceous earth in a finely divided state, intermixed withfinely divided asbestos in either a raw, uncalcined or in a calcined state, is adapted to be used in dry form and without being first moistened or molded, as a heat insulating material or filler for blast furnace walls, or ovens, or 110 for other similar structures or purposes.

After the material containing the diatomaceous earth, or diatomaceous earth and asbestos with or without the binder, composed of bondinaclay or equivalent or similar material, has been calcined or burned before being molded, and then molded,--or whether molded or notthe article or articles thus obtained may be again burned or calcined, or subjected to the action of great heat, either in the operation of further burning the same or while in actual use for heatinsulating or heat-resisting purposes, without causing the material or article or articles or structures thus obtained to shrink,

obtained, may thus be obtained by calcining or burning the material-either the d1atomaceous earth before mixing it with the asbestos, or both the diatomaceous earth and asbestos both in a finely divided statebefore molding or using the same. And a non-shrinking nonwarpmg structure is thus obtained.

The advantage and importance of thus being able to obtain finished articles or structures of the exact size and dimensions desired, and uniformly burned or calcined throughout regardless of the dimensions or thickness of such articles, and the freedom from shrinkage, warping anddistortion thus obtained will be readily understood and appreciated by those skilled in the art.

By calcining or burning the material before molding, less time is required in burning or calcining than is the case when the material is molded before being calcined, baked or burned.

From the foregoing description it will be readily understood that the material or mixture comprising diatomaceous earth, or diatomaceous earth and a binder, such, for instance, as refractory or bonding clay, or diatomaceous earth calcined or burned and then intermixed with finely divided asbestos in either raw or baked, calcined or burned condition, the calcined diatomaceous earth being also disintegrated, or in a finely divided condition,whether used in dry form,

or molded or formed, or intended to be moistened and molded or formed or spread or applied in the form of a cement or otherwise, after the calcining, baking or burning of the diatomaceous earth or the mixture,-

may contain said materials in any suitable proportions, and may be burned for any desired length of time and at any desired suitable temperature such as Will result in the production of a simple, economical and efficient heat-insulating composition or material, when treated in the manner herein described.

I have found in practice that a mixture containing finely divided calcined diatomaceous earth approximately 75 per cent; as-

bestos finely divided or fibrous, either baked and calcined orraW and unbaked, but, by preference, calcined, baked or burned as above described, approximately 25 per cent; and either with or without a binder such as refractory or bonding clay equivalent in bulk to approximately 3 per cent. to 10 per cent. of the mass of diatomaceous earth and asbestos, all intermixed, and either in dry form, or moistened and molded, by preference, while subjected to suitable pressure as already indicated, or formed into the desired shape, is satisfactory for the purposes for which the material and article or structures containing the same are intended.

In the finished product the diatomaceous earth serves as a very efficient heat-resisting or heat-insulating medium; the asbestos, being of a fibrous nature, serves to some extent as a binder, and also as a refractory fireproof or heat-resisting medium; and said elements, intermixed and calcined, form a light, strong cellularstructure or heat-insulating body. The binder, consisting of'or containing refractory bonding clay or its equivalent, serves to hold the particles of finely divided calcined diatomaceous earth and the particles of asbestos in rigid adhesive or cohering contact or relation, and also serves as a heat-resisting medium, and adds to the strength of the structure.

When the material is intended to be used as a cement, it should, of course, be softened or rendered plastic by moistening to a greater extent or by the introduction of a larger proportion of liquid or binding material than when prepared for molding.

The texture of the finished product, whether consisting of intermixed calcined diatomaceous earth in a finely divided state and finely divided asbestos intermixed and forming a compound which has never been moistened or m'olded but packed as it would be when in use as a filler for a blast furnace Wall or oven wall, or similar structure, or as it would appear when compressed into the form of a brick or heat-insulating block, is such that a multiplicity of minute air cells are present in the material.

- A form of my heat-insulating compound raw and uncalcined, or calcined, approximately 25 per cent, intermixed and compressed together in dry form, or slightly moistened with water, or water and a suitable binder containing bonding clay, and

compressed into the position in which the material is intended to be used and allowed to dry. Very satisfactory results are accomplished in practice by using the intermixed calcined diatomaceous earth and asbestos in dry form as a filler, without moistening, and without the introduction of a binder of bonding clay or similar material.

I claim:

1. A heat-insulating composition consisting of finely divided calcined diatomaceous earth, and finely divided asbestos, intermixed and forming a heat-resisting material,

2. A heat-insulating composition consistzttoinaceous earth and asbestos being in ad- 10 ing of finely divided calcined diatomaceous liesive contact and forming a rigid body. earth, and finely divided calcined asbestos, Signed at Milwaukee, in the county of intermixed and forininga, heat-resisting 1J12L- Milwaukee, and State of Wisconsin, this terial. 28th day of September, 1918.

3. A heat-insulating brick formed of a FRANK A. HEADSON. heat-resisting composition consisting of finely Witnesses divided calcined diatomaceous earth and C. R. MANVILLE, finely divided asbestos, the particles of di- ALB. S. MILLS. 

